1. Field of the Invention
The disclosures herein relate to a fixing device and an image forming apparatus.
2. Description of the Related Art
In an image forming apparatus employing an electrophotographic system such as a printer, a copier, a facsimile machine, a multifunctional peripheral, and the like, a photoreceptor is initially charged by a charging device, a latent image is then formed on the photoreceptor by exposure of an original image or optically writing an image based on image information. The latent image is then developed by a developing device using toner to convert the latent image into a visible image, that is, a toner image, and then the toner image is transferred onto a recording sheet of paper serving as a transfer material. The sheet carrying merely transferred unfixed toner image is then passed through a fixing device to fix the unfixed toner image onto the sheet, and thus a copy or print of the image is obtained as a result.
A typical and well known fixing device used in such an image forming apparatus includes a fixing roller having a heat source (fixing roller having a built-in heater or self-heating fixing roller), a fixing belt looped over the fixing roller, and a pressure roller rotated by contacting the fixing belt or the fixing roller. In such a fixing device, the recording medium (transfer material) carrying the unfixed toner image is transferred by being sandwiched between the fixing roller and the pressure roller, where the fixing roller and the pressure roller pressure contact the unfixed toner image carried on the recording medium and the unfixed image is thus fixed to the recording medium. Further, it is also well-known in the art that a heating roller having an internal heater, and a tension roller applying tension to the fixing belt are disposed inside the fixing belt other than the fixing roller.
In such a fixing device, a belt of the fixing belt or a roller of the fixing roller is generally replaced with a new one when the belt or the roller is degraded or worn with time, or accidentally damaged. However, compared to the fixing roller, the fixing device having the fixing belt may exhibit a longer downtime because the fixing belt may require a longer replacing time or a roller may be damaged while the belt is replaced due to its complicated configuration.
The related art fixing device generally includes an integrated structure of heating roller holding members supporting a heating roller with a case or the like of the fixing device. In this configuration, to replace the fixing belt or the like, the heating roller holding members are removed from the case, and the heating roller is then removed from the fixing device. Further, after heating roller bearings and insulating bushing attached to a shaft of the heating roller are removed from the heating roller, the heating roller is drawn out from the fixing device, and the fixing belt and the fixing roller are detached thereafter.
Japanese Laid-open Patent Publication No. 2011-197019 (hereinafter referred to as “Patent Document 1”), for example, discloses a technology to form an endless belt unit in which a fixing belt is attached to opposite ends in an axial direction of reinforcement members, a fixing nip forming unit is inserted in an axial direction between the reinforcement members projected from side faces of a flange and the fixing belt, which forms the endless belt unit as a result. In this disclosed configuration, a flange of the endless belt unit is configured to be attached or detached with respect to a frame of the fixing device, which allows the endless belt unit to be attached or detached with respect to the frame of the fixing device. A nip forming unit is removed from a side of the flange of the endless belt unit detached from the frame of the fixing device.
However, the related art fixing device may require a longer time for replacing the belt or the like because the heating roller is removed only after the components attached to the shaft of the heating roller are removed. Further, the heating roller may need to be drawn out from the fixing belt in an axial direction before the fixing belt is detached. Hence, interference between the heating roller and the fixing belt while the heating roller is being drawn out may damage the fixing belt.
Further, in the technology disclosed in patent Document 1, a longer time may be required for inserting the flange of the endless belt unit into the frame of the fixing device in order to replace the fixing belt of the endless belt unit composed of the reinforcement member and the flange for attaching the fixing belt. The heating roller may need to be drawn out from the frame of the fixing device in an axial direction before the fixing belt is detached. Hence, interference between the heating roller and the fixing belt while the heating roller is being drawn out may damage the fixing belt.
Further, the heating roller may need to be drawn out from the fixing belt in an axial direction before the fixing belt is detached. Hence, interference between the heating roller and the fixing belt while the heating roller is being drawn out may damage the fixing belt. Moreover, in this configuration, a longer time may be required for replacing the fixing belt with a new one.